The feature is now available to all of our users on LinkedIn to integrate a twitter account.
When you are signed in, check the Twitter box under your Network Updates box on the homepage and follow a few simple steps.
Clicking through the setup process will allow you to specify the Twitter account that you’d like to sync and/or display on your LinkedIn profile.
As part of the setup process, you can choose to either send all your tweets or select tweets from Twitter back to LinkedIn as a status update.
You can choose to share all or just tweets that you tag with #in at the end (similar to #fb for facebook)